Changes in skeletal muscle in males and females following endurance training

• Published in: Canadian journal of physiology and pharmacology Vol. 79; no. 5; pp. 386 - 392
• Main Authors: Carter, S L, Rennie, C D, Hamilton, S J, Tarnopolsky, M A
• Format: Journal Article
• Language: English
• Published: Ottawa, Canada NRC Research Press 01.05.2001; National Research Council of Canada; Canadian Science Publishing NRC Research Press
• Subjects: Adult; Aerobics; Biological and medical sciences; Biopsy; Body Composition; Body Weight; Citric Acid Cycle; Electron Transport; Electron Transport Complex IV - metabolism; Enzymes; Exercise Test; Female; Fundamental and applied biological sciences. Psychology; Gender; Humans; Male; Muscle Fibers, Skeletal - cytology; Muscle, Skeletal - cytology; Muscle, Skeletal - enzymology; Muscle, Skeletal - physiology; Muscles; Oxygen Consumption; Physical Endurance - physiology; Physical Fitness; R&D; Research & development; Sex Characteristics; Striated muscle. Tendons; Vertebrates: osteoarticular system, musculoskeletal system; Physical exercise; Human; Vastus lateralis muscle; Physical training; Bicycle ergometer; Environmental factor; Male; Muscular fiber; Striated muscle; Enzymatic activity; β Oxidation; Female; Endurance; Comparative study
• ISSN: 0008-4212; 1205-7541
• DOI: 10.1139/y01-008

Gender differences in substrate selection have been reported during endurance exercise. To date, no studies have looked at muscle enzyme adaptations following endurance exercise training in both genders. We investigated the effect of a 7-week endurance exercise training program on the activity of β-oxidation, tricarboxylic acid cycle and electron transport chain enzymes, and fiber type distribution in males and females. Training resulted in an increase in O 2 peak for both males and females of 17% and 22%, respectively (P < 0.001). The following muscle enzyme activities increased similarly in both genders: 3- β-hydroxyacyl CoA dehydrogenase (38%), citrate synthase (41%), succinate-cytochrome c oxidoreductase (41%), and cytochrome c oxidase (COX; 26%). The increase in COX activity was correlated (R 2 = 0.52, P < 0.05) with the increase in O 2 peak / fat free mass. Fiber area, size, and % area were not affected by training for either gender, however, males had larger Type II fibers (P < 0.05) and females had a greater Type I fiber % area (P < 0.05). Endurance training resulted in similar increases in skeletal muscle oxidative potential for both males and females. Training did not affect fiber type distribution or size in either gender.Key words: endurance training, oxidative potential, gender.